Drill steel

ABSTRACT

A DRILL STEEL HAVING AN IMPROVED THREADING ARRANGEMENT THEREON WHEREIN A PLURALITY OF SPACED THREADED PORTIONS ARE PROVIDED ON THE DRILL STEEL ELEMENT AND SEPARATED BY UNTHREADED PORTIONS SO AS TO ALLOW REMOVING A WORN SECTION OF THE ELEMENT AND RECOUPLING THE ELEMENT WITH ANOTHER OF SAID THREADED PORTIONS.

arch 1971 T. A. PARSSINEN DRILL STEEL v Filed Dec. 5, 1968 l/VVE/V TOR TOIM/ A PARSSI/VE/V United States Patent 3,567,254 DRILL STEEL Toimi A. Parssinen, R.F.D. 1-165, Newport, N .H. 03773 Filed Dec. 3, 1968, Ser. No. 780,791 Int. Cl. E21b 17/02 US. Cl. 287-117 3 Claims ABSTRACT OF THE DISCLOSURE Some drill steel strings used with reverse rotation percussion drills, rotary percussion drills, or the like are continuously threaded around the outer periphery thereof and have coupling members which releasably secure adjacent longitudinal sections or sectionals of the string together at the axial ends thereof. The continued pounding and rotating of the string causes the threaded ends of the sectionals which were enveloped by the coupling members to wear, thereby necessitating reconditioning the sectionals by removing the worn sections therefrom and then recoupling the reconditioned sectionals.

The reconditioned recoupled string must have provisions to prevent the coupling portion from running down the string and various structures have been devised for this purpose, none of which has proved completely satisfactory. One of these structures includes using couplings threaded halfway through from each end with the threads purposely mismatched, however, with some thread types under certain conditions the mismatched threads ultimately wear enough to be useless in preventing the problem. Another structure includes the use of a bridge coupling which when interposed between sectional ends results in much of the drilling energy being wasted by dissipation through the coupling and, additionally this excess energy in the coupling causes heating and premature failure thereof.

The drill steel string of the present invention provides threaded relief portions which allow the reconditioning of the worn sections by cutting at such relief portions in such a way as to produce button bearing ends at the reconditioned sectionals.

These and other objects and advantages of this invention will become more readily apparent to those skilled in the art upon the reading of the following detailed description and drawings in which:

FIG. 1 is a side view of a drill steel string and coupling member embodying the principles of this invention;

FIG. 2 is a fragmentary view, partly in section, of the drill steel and coupling member shown in FIG. 1;

FIG. 3 is a side view of another embodiment of a drill steel string and coupling member of this invention;

FIG. 4 is a fragmentary view, partly in section of the drill steel and coupling member shown in FIG. 1; and

FIG. 5 is a fragmentary view, partly in section, of another embodiment of a drill steel string and coupling member of this invention.

Referring to FIG. 1, a hollow elongated drill steel string, generally indicated at 10, is a type commonly used with reverse rotation rock drills, rotary percussion drills, or other well known drilling equipment and comprises a plurality of hollow elongated generally cylindrical drill steel elements or sectionals 12 which are releasably secured at the axial ends thereof by elongated hollow cylindrical coupling members 14. Coupling members 14 "ice additionally secure respective ends of the string 10 to a well known drill (not shown) and a well known drill bit portion (not shown). With such an arrangement as hereinabove described, as the drill steel string 10 progresses further into a drill hole, a drill operator can increase the length of the string 10 by coupling an additional sectional 12 thereto.

Sectionals 12 comprise a plurality of elongated inter mediate sections 16 and end sections 1 8, each of such sections being separated from one another at the axial ends thereof by collar portions 20. Sections 16 include: an intermediate portion 22 having threads around the outer periphery thereof, such threads shown as male rope threads 24 which have a major diameter thereof slightly smaller than the outside diameter of collar portion 20; and recessed or thread relief portions 26 at the axial ends of section 16 axially adjacent the intermediate portion 22 and collar portions 20.

Thread relief portions 26 resemble a flat bottomed groove about the outer periphery of sections 12 such that a view thereof transverse to the longitudinal axis of a section 12 shows portion 26 comprised of: a flat groove bottom 30 having a diameter thereof equal to or slightly smaller than the minor diameter of threads 24; and arcuate sides 32 and 34 which radiate outward from the longitudinal ends of bottom 30, respectively to an end of collar portion 20 and the end of the rope thread 24 which is adjacent relief portion 26.

The end sections 18 comprise those portions hereinabove described with reference to sections 16 with a primary exception being that a relief portion 36 at the free end of each section 18 is substituted for a relief portion 26 hereinabove described with reference to section 16. Such a portion 36 comprises a fiat groove bottom 38 having a diameter thereof equal to the diameter of bottom 30 which, bottom 38, extends rearward from the free end of section 18 a distance equal to or less than the longitudinal extent of bottom 30; and a rear arcuate side 40 which radiates outwardly and rearwardly from the rear end of bottom 38 to the end of the rope thread 24 adjacent relief portion 36.

Coupling members 14 have female rope threads 42 about the entire inner periphery thereof. Female threads 42 are dimensioned to be engageable with male rope threads 24 of sectionals 12 thereby permitting the coupling of two members 12 by threading end sections 18 into opposite ends of member 14 until bearing contact of such sections occurs intermediate the axial ends of the member 14. With the sectionals butting together a substantial portion of the drilling energy is passed directly through sectionals 12 to the drill bit (not shown) because of the bearing contact of adjacent coupled sectionals 12. Additionally, the coupling members 14 are prevented from traveling down the drill steel towards the drill bit by the collar portion 20 for the outside diameter thereof is slightly larger than the major diameter of the female threads 42. Such tendency to travel occurs as a result of .a variety of internal and external forces applied to the drill string 10.

FIG. 2 shows a preferred coupling arrangement as hereinabove described wherein: the length of member 14 is approximately twice the length of the summation of an intermediate threaded portion 22 and a thread relief portion 36; and an end of member 14 has the inner periphery thereof in contact with one of the coupled sectionals 12, which in practice would be that sectional 12 closest to the drill bit (not shown), adjacent a collar portion 20 thereof which, collar portion 20, restricts any downward travel of member 14 as hereinabove described. It is to be noted that although the maximum length of coupling member 14 is obviously controlled by the length of end sections 18, a length thereof less than such maximum length can be used if factors such as thread capacity, moment-deflection considerations and the like are evaluated in obtaining such lesser length.

During a drilling operation drill steel is subjected to a variety of internal and external forces, for example tension and compression forces applied along the longitudinal axis thereof and bending moment applied transverse to the longitudinal axis. As a result of such forces the coupled end sections 18 wear at the threaded portions 22 thereof thereby resulting in the coupling members 14 becoming loose with respect to sectionals 12. To alleviate the problem of such loose coupling members 14, the sectionals 12 must be uncoupled and reconditioned at the worn ends thereof.

To recondition the sectionals 12, the worn section 18 is removed by any suitable cutting technique, for example cold cutting, flame cutting, burning and the like. The cut through the sectional 12 is made at the end of a groove bottom adjacent the arcuate side 32 of the section 16 which is adjacent the worn section 18. Thus with such removing, the adjacent section 16 is transformed into an end section 18 and the sectionals 12 are then recoupled in a manner hereinbefore described until bearing contact is made. In practice the new sections 18 will have the free ends thereof finished in any suitable manner as by chamfering to insure full hearing when coupled.

FIGS. 3 and 4 illustrate another embodiment of the present invention. Inasmuch as this embodiment resembles the embodiment hereinbefore illustrated, similar elements will be given the same reference numerals primed.

Referring to FIG. 3, a hollow elongated drill steel string generally indicated at 10 comprises a plurality of elongated hollow generally cylindrical drill steel elements or sectionals 12' which are releasably secured together at the ends thereof by an elongated hollow coupling member 14'.

Sectionals 12' comprise a plurality of elongated intermediate sections 16 and end sections 18', each of such sections being separated from one another at the axial ends thereof by thread relief portions 26'. Sections 16' have threads about the outer periphery thereof, such threads shown as male rope threads 24'. The threads 24' of adjacent sections 16 are mismatched along the helical path of the thread by substantially one-half turn.

Thread relief portions 26 resemble a flat bottom groove about the outer periphery of sectionals 12 such that a view thereof transverse to the longitudinal axis of a sectional 12' shows portions 26' comprised of a flat groove bottom 30' having a diameter thereof equal to or slightly smaller than the minor diameter of threads 24; and arcuate sides 32 and 34' which radiate outward from the longitudinal ends of bottom 30', respectively to the ends of rope threads 24' which are adjacent relief portion 26'.

End sections 18 include an elongated portion 44 having male rope threads 24' around the outer periphery thereof; and a thread relief portion 36' at the free ends thereof. Portion 36 comprises a flat groove bottom 38 having a diameter thereof equal to the diameter of bottom 30' which, bottom 38 extends rearward from the free end of section 18 a distance equal to or less than the longitudinal extent of the bottom 30'; and a rear arcuate side 40 which radiates outwardly and rearwardly from the rear end of bottom 38' to the end of a rope thread 24' adjacent relief portion 36.

Coupling members 14' have female rope threads 42' about the entire inner periphery thereof with the exception of a zero helix angle thread or inwardly projecting collar portion 48 which is located intermediate the axial ends of member 14. Female threads 42' are dimensioned to be engageable with male rope threads 24' of sectionals 12' thereby permitting the coupling of sectionals 12 by threading end sections 18 into opposite ends of member 14' until bearing Contact of such sections occur intermediate the axial ends of the member 14. With such a coupling arrangement a substantial portion of the drilling energy is passed directly through sectionals 12' to the drill bit (not shown) because of the bearing contact of adjacent coupled sectionals 12. Additionally, the coupling members 14' are prevented from traveling down the drill steel towards the drill bit by the collar portion 48, for the diameter of the innermost extent thereof is slightly larger than the major diameter of the female threads 42. Such tendency to travel occurs as a result of a variety of internal and external forces applied to the drill string 10.

FIG. 4 shows a preferred coupling arrangement as hereinabove described wherein: the length of member 14 is approximately twice the length of an end section 18'; and a side 40' of an end section 18 is in contact with projection portion 48, which in practice would be the side 40' of the end section 18' closest to the drill bit (not shown). It is to be noted that although the maximum length of the coupling member 14 is obviously controlled by the length of the end sections 18, a length thereof less than such maximum length can be used if factors such as thread capacity, moment deflection and considerations and the like are evaluated in obtaining such lesser length.

Internal and external forces hereinbefore described with reference to drill steel 10 necessitate reconditioning of the sectionals 12' by initially removing the worn section 18' by any suitable cutting technique, for example cold cutting, flame cutting, burning and the like. The cut through the sectional 12 is made at the end of a groove bottom 30 adjacent the arcuate side 32 of the section 16' which is adjacent the worn section 18. Thus with such removing, the adjacent section 16' is transformed into an end section 18' and the sectionals 12 are then recoupled in a manner hereinbefore described until bearing contact is made. In practice the new sections 18' have the free ends thereof finished in any suitable manner to insure full bearing contact when coupled.

FIG. 5 illustrates still another embodiment of the present invention which is quite similar in appearance and operation to the embodiment hereinbefore discussed with reference to FIGS. 1 and 2 with the primary difference between the two embodiments being that the collar portion 20" has only one thread relief portion 26 adjacent a side thereof rather than relief portions 26 adjacent both sides of threaded portion 20 as is the case with the embodiment illustrated in FIGS. 1 and 2. The relief portion 26" is adjacent the side of collar portion 20" furthest from the coupled end of the sectional 12". The absence of a relief portion 26" on both sides of threaded portion 20 results in the sectional '12" being capable of only one orientation with regards to an adjacent sectional 12" rather than a dual orientation which is permitted by the embodiment of sectional '12 illustrated in FIGS. 1 and 2. A worn sectional 12" is reconditioned in a similar manner as hereinbefore discussed with regards to sectional 12.

Although preferred embodiments of this invention have been described and illustrated herein, modifications are contemplated such as: the substitution of male and female reverse buttress threads for the rope threads hereinbefore discussed; and the sectionals do not necessarily have to have threaded sections along the entire length thereof but can have plural threaded sections on the end portions of such sectionals or can have alternately threaded and unthreaded sections.

The description herein does not limit the structure of this invention and the invention is defined by the scope of the claims set forth hereinafter.

What is claimed is:

1. A drill string for use with a percussion drill comprising; an elongated drill steel element having at least one end portion on which there are a plurality of axially spaced discrete externally threaded portions separated by unthreaded portions; at least a portion of each of said unthreaded portions is a collar of the same diameter as full size portions of said drill steel element before threading, and each said unthreaded portions comprises said collar portion spaced from at least one of the adjacent ones of said threaded portions by a recessed unthreaded portion having a diameter not greater than the minor diameter of said threaded portion.

2. A drill string for use with a percussion drill comprising; an elongated drill steel element having at least one end portion on which there are a plurality of axially spaced discrete externally threaded portions separated by unthreaded portions, said drill steel element is coupled to a similar drill steel element in abutting axial aligned relationship by an elongated hollow cylindrical internally threaded coupling element, said coupling element is provided With spaced portions of the internally threaded portion extending inwardly from each end of said coupling and having a helical angle equal to the helical angle of said externally threaded portion, said internally threaded portions being separated by a similarly formed internal thread having a zero helix angle.

3.'A drill steel as specified in claim 1 wherein each end of said drill steel element has a reduced diameter unth'readed portion equal in diameter and of no greater length than one of said recessed unthreaded portions.

References Cited UNITED STATES PATENTS 717,684 1/1903 Humphreys 287-117 1,849,075 3/1932 Dardelet 287- 1,970,673 8/1934 Rea 287-117 2,668,966 2/1954 Corlett et a1. 151-70 2,670,022 2/1954 Oldberg et a1 15170 3,211,484 10/1965 Karlsson et a1. 287-117 DAVID J. WILLIAMOWSKY, Primary Examiner A. V. KUNDRAT, Assistant Examiner US. Cl. X.R. 285355, 390 

